Polylactide (PLA)-clay nanocomposites prepared by melt compounding in the presence of a chain extender

Polylactide-layered silicate nanocomposites with and without a chain extender were prepared by melt mixing using a twin-screw extruder. An organo-modified clay, Cloisite (R) 30B, and a chain extender Joncryl (R)-ADR 4368F were employed in this study. The effect of the chain extender and processing conditions on the properties of the PLA-clay nanocomposites were investigated for different strategies of mixing. The resulting nanocomposites were characterized by X-ray diffraction (XRD), while their morphology was observed by SEM and TEM. The incorporation of the chain extender could enhance the degree of clay dispersion provided that it is judiciously added to the nanocomposite. The corresponding results revealed that the Joncryl-based nanocomposites, where nanoclay platelets were well-dispersed, exhibited a significantly reduced permeability as compared to others. The mechanical properties of the neat PLA, the PLA and Joncryl-based nanocomposites were also examined. The increased molecular weight in Joncryl-based nanocomposites caused a significant increase in the modulus, drawability and toughness of the samples. (C) 2012 Elsevier Ltd. All rights reserved.